Aromatic are important starting substances for the preparation of organic bioactive agents or their intermediates, since these can readily be employed in C-C coupling reactions, reductions or in other derivatizations on account of the reactive aldehyde function [Organikum, 21st edition; Wiley-VCH Verlag, 2001 pages 456-622 (ISBN 3-527-29985-8)].
The palladium-catalysed carbonylations of aryl bromides or iodides for the production of aromatic carboxylic acids [L. Cassar, M. Foa, A. Gardano, J. Organomet. Chem. 1976, 121, C55], esters [A. Schoenberg, I. Bartoletti, R. F. Heck, J. Org. Chem. 1974, 39, 3318; J. K. Stille, P. K. Wong, ibid., 1975, 40, 532; M. Hidai, T. Hikita, Y. Wada, Y. Fujikura, Y. Uchida, Bull. Chem. Soc. Jpn. 1975, 48, 2075; T. Ito, K. Mori, T. Mizoroki, A. Ozaki, ibid., 1975, 48, 2091], amides, [A. Schoenberg, R. F. Heck, J. Org. Chem. 1974, 39, 3327], α-oxo amides [T. Kobayashi, M. Tanaka, J. Organomet. Chem. 1982, 233, C64; F. Ozawa, H. Soyama, H. Yanagihara, I. Aoyama, H. Takino, K. Izawa, T. Yamamoto, A. Yamamoto, J. Am. Chem. Soc. 1985, 107, 3235], α-oxo esters [M. Tanaka, T. A. Kobayashi, F. Skakura, N. Itatani, S. Danno, K. Zushi, J. Mol. Cat. 1985, 32, 115; B. Morin, A. Hirschauer, F. Hugues, D. Commereuc, Y. Chauvin, J. Mol. Cat. 1986, 34, 317] und α-oxo acids [M. Tanaka, T. A. Kobayashi, T. Sakakura, J. Chem. Soc., Chem. Commun. 1985, 837] are known. In particular, the preparation of substituted benz is of interest on account of the further possibilities of use as synthesis units.
In the literature, the reductive palladium-catalysed carbonylation of halogenated aromatics, heterocycles and vinyls is mentioned for the first time by Heck et al. 1974 [A. Schoenberg, R. F. Heck, J. Am. Chem. Soc. 1974, 96, 7761-7764]. The authors observed that the reaction is essentially restricted to aryl halides, which can only undergo a β-hydride elimination with difficulty. The reaction conditions described extend over a large temperature range (80-150° C.), the dehalogenation mentioned beforehand being able to increase with temperature in a substrate-dependent manner. Pressures of over 80 bar (CO/H2 1:1) likewise increase the yields.
In the same year, a corresponding patent was filed [U.S. Pat. No. 3,960,932, R. F. Heck, 1974]. Stille et al. were able to convert a series of organic halides into the corresponding in the presence of Bu3SnH and Pd catalyst [V. P. Baillard-Geon, J. K. Stille, J. Am. Chem. Soc. 1983, 105 (24), 7175-7176]. The process has the advantage that the corresponding result even in the presence of other reactive functional groups.
In DE 3242582, EP 244328 and EP 244329, processes for the palladium-catalysed conversion of haloaromatics, in particular bromo- and iodoaromatics, to aromatic in the presence of synthesis gas are disclosed. In these specifications, mainly a few process technology details are emphasized. In JP 10-330307, the palladium-catalysed reductive carbonylation of bromo- or iodoaromatics in the presence of a palladium catalyst is likewise demonstrated. As a monodentate ligand, tris-tert-butylphosphane is employed. It is reported that this ligand especially helps to achieve unexpectedly high yields of product. The ligand used, however, is pyrophoric and therefore cannot be employed advantageously on a large scale.
DE 10037961 generally discloses adamantyl-substituted phosphane compounds as ligands for, inter alia, carbonylation reactions of haloaromatics. Application to Hal′-substituted (hetero)aromatics in reductive carbonylation has, however, not been explicitly described here.
The object of the present invention was therefore to make available a process which is suitable, in particular on the industrial scale, for the conversion of Hal′-substituted (hetero)aromatics to aromatic in a more advantageous manner compared to the prior art. Very particularly, the process in mind should have advantages with respect to yield, by-product spectrum and handle-ability of the compounds, also from industrial safety points of view. Moreover, seen from the economic and ecological standpoint, it should be superior to the prior art processes.